/*
 * Copyright 2012-2013 MyBatis.org.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.ibatis.builder;

import java.util.HashMap;

/**
 * Inline parameter expression parser. Supported grammar (simplified):
 * 
 * <pre>
 * inline-parameter = (propertyName | expression) oldJdbcType attributes
 * propertyName = /expression language's property navigation path/
 * expression = '(' /expression language's expression/ ')'
 * oldJdbcType = ':' /any valid jdbc type/
 * attributes = (',' attribute)*
 * attribute = name '=' value
 * </pre>
 */
/**
 * @author Frank D. Martinez [mnesarco]
 */
public class ParameterExpression extends
		HashMap<String, String> {

	private static final long serialVersionUID = -2417552199605158680L;

	public ParameterExpression(
			String expression) {
		parse(expression);
	}

	private void parse(String expression) {
		int p = skipWS(expression, 0);
		if (expression.charAt(p) == '(') {
			expression(expression,
					p + 1);
		} else {
			property(expression, p);
		}
	}

	private void expression(
			String expression, int left) {
		int match = 1;
		int right = left + 1;
		while (match > 0) {
			if (expression
					.charAt(right) == ')') {
				match--;
			} else if (expression
					.charAt(right) == '(') {
				match++;
			}
			right++;
		}
		put("expression",
				expression
						.substring(
								left,
								right - 1));
		jdbcTypeOpt(expression, right);
	}

	private void property(
			String expression, int left) {
		if (left < expression.length()) {
			int right = skipUntil(
					expression, left,
					",:");
			put("property",
					trimmedStr(
							expression,
							left, right));
			jdbcTypeOpt(expression,
					right);
		}
	}

	private int skipWS(
			String expression, int p) {
		for (int i = p; i < expression
				.length(); i++) {
			if (expression.charAt(i) > 0x20) {
				return i;
			}
		}
		return expression.length();
	}

	private int skipUntil(
			String expression, int p,
			final String endChars) {
		for (int i = p; i < expression
				.length(); i++) {
			char c = expression
					.charAt(i);
			if (endChars.indexOf(c) > -1) {
				return i;
			}
		}
		return expression.length();
	}

	private void jdbcTypeOpt(
			String expression, int p) {
		p = skipWS(expression, p);
		if (p < expression.length()) {
			if (expression.charAt(p) == ':') {
				jdbcType(expression,
						p + 1);
			} else if (expression
					.charAt(p) == ',') {
				option(expression,
						p + 1);
			} else {
				throw new BuilderException(
						"Parsing error in {"
								+ new String(
										expression)
								+ "} in position "
								+ p);
			}
		}
	}

	private void jdbcType(
			String expression, int p) {
		int left = skipWS(expression, p);
		int right = skipUntil(
				expression, left, ",");
		if (right > left) {
			put("jdbcType",
					trimmedStr(
							expression,
							left, right));
		} else {
			throw new BuilderException(
					"Parsing error in {"
							+ new String(
									expression)
							+ "} in position "
							+ p);
		}
		option(expression, right + 1);
	}

	private void option(
			String expression, int p) {
		int left = skipWS(expression, p);
		if (left < expression.length()) {
			int right = skipUntil(
					expression, left,
					"=");
			String name = trimmedStr(
					expression, left,
					right);
			left = right + 1;
			right = skipUntil(
					expression, left,
					",");
			String value = trimmedStr(
					expression, left,
					right);
			put(name, value);
			option(expression,
					right + 1);
		}
	}

	private String trimmedStr(
			String str, int start,
			int end) {
		while (str.charAt(start) <= 0x20) {
			start++;
		}
		while (str.charAt(end - 1) <= 0x20) {
			end--;
		}
		return start >= end ? "" : str
				.substring(start, end);
	}

}
